A wide range of mowers are available to New Zealand farmers. Tim McVeagh checks out some of the offerings.

The New Zealand dairy farmer has an impressive range of mowers to pick from, with Krone alone having 35 models on their website. With a range of features varying between models, there’s a fair bit to take in.

Working widths range from two to 10 metres. They can be drum or disc mowers. They can be front, rear, side-mounted, or a combination of these, while the bigger units tend to be trailed, or even self-propelled.

‘A refined hay mower used for topping gets a heluva hard time due the amount of shit they thrash through, along with stones.’

A good place to start the selection process, as always, is to define the needs, wants, and limitations, specifically:

What crops are to be mown? Will this be limited to pasture, or include lucerne or other crops?

  • What area will be mown each year?
  • Will the mower be used for topping?
  • What horsepower tractor will be used?
  • Is a conditioner needed?

The ideal mower will:

  • be easily attached and removed,
  • provide a clean cut at the range of heights required, without scalping or striping,
  • top as well as mow, as required,
  • be easy and safe to operate,
  • have low maintenance requirements,
  • have reasonable horsepower requirements,
  • allow spreading or windrowing of pasture if needed,
  • have mechanisms to prevent damage when an obstacle like a post is hit, or when an object like a rock or wire is picked up,
  • come with a reasonable warranty, spare parts availability, after sales service.
  • come at a reasonable cost.
Most hay mowers bought by dairy farmers are disc mowers like this Kverneland model.

The Basics:

The basic differences between mowers are drum and disc; mounting, (front, rear, side, trailed, self-propelled); and whether fitted with a conditioner.

Drum and disc: Drum mowers have two to four belt or shaft-driven rotors, each fitted with knives. Their proponents say drum mowers are equally suited to mowing or topping, are less complex, have lower horsepower requirements, and can to some extent windrow the crop. Disc mowers have a series of discs mounted on a cutter bar, each with a pair of knives. They are usually driven by a series of gears within the cutter bar. The cutter bar may be shaft or belt-driven. Disc mowers can be compact, angular or spur drive in the bar. Their proponents claim a cleaner cut so better pasture recovery, less striping, and wider and so more efficient mowers are possible. Most hay mowers available in NZ now are disc mowers. They can be used for topping, some by fitting topping skids.

Mounting: Most mowers bought by dairy farmers are side-mounted on the three-point linkage. Front-mounted units are usually used in conjunction with a pair of rear-mounted mowers to give maximum mowing width. Some smaller units are rear-mounted, (directly behind the tractor) with their advocates saying they are safer under some conditions, easier to manoeuvre, and quicker when switching between mowing and travelling. Trailed and self-propelled mowers are more commonly bought by contractors or those doing a lot of mowing.

Conditioners: Conditioning helps dry out the crop, so is common where drying time is more critical. Models like some in the Massey Ferguson range can be retrofitted with a tine or roller conditioner. Some can be set to send the crop into a windrow. Running a mower with a conditioner requires more power.

Tine conditioners have vee-shaped tines in a spiral pattern, are fairly aggressive, and are more suitable for grass crops. Conditioning intensity for different crops is set by a baffle plate. Tines can be either steel or nylon, with steel tines lasting longer but taking a little more horsepower due to their weight. Flexible mounting of steel tines reduces damage by objects like stones.

Roller conditioners crush the stalks and expose the pith so it can dry out faster, but leave as much leaf intact as possible. They have either steel, polyurethane, or rubber rollers. Rubber or polyurethane rollers are suitable for leafy crops like lucerne and clover. Steel rollers are more suitable for thick-stemmed crops, and last longer than rubber ones. Conditioner speed may be adjustable to cater for different crops. An adjustable spring loading mechanism can vary the conditioning intensity, and protect the rollers from foreign objects.

Maxam claim their wilter spreaders allow faster drying of crops than conditioners.

The Maxam 3300IV is the only drum mower in the list of models suggested for larger dairy farms. The twin wilters spread the pasture out for quicker drying. Maxam claim their mowers fitted with the Wilter Spreader are the only mowers that can cut, condition, and spread pasture in one pass without driving on the cut crop.

Further features to consider:

Horsepower requirement for the tractor. Most quote tractor power requirement, (in horsepower), with a few suppliers quoting PTO power requirement. These are significantly different; for example the Kuhn GMD 4411 has a tractor power requirement of 61hp, (45kW); and a PTO power requirement of 45hp, (34kW).

Hydraulic requirements for the tractor. This starts with basic models requiring one single- acting hydraulic coupling.

Working width and mowing width. Either or both of these are quoted for mowers.

Centre-mounted pivot mowers. The attachment point for these mowers is at the centre of the mower, rather than at the near end. This allows a smoother ride and so a more consistent mowing pattern.

Capacity: Mowing capacity in ha/hr is quoted by some suppliers but can vary considerably with crop weight, type, and moisture content. Figures quoted in brochures should be based on objective data. In other cases an estimate has been made for the mowing capacities quoted in Table 1 and 2. The best advice in buying a mower would be to get an objective figure for any situation based on trial work or experience.

Topping. Topping may mean fitting topping skids, or adjusting the mower height. Pre-grazing topping is carried out by some farmers but all DairyNZ’s research indicates that there is no benefit where pasture management, (residual left after grazing) is sound, and there is a cost in terms of time and running costs.

“A refined hay mower used for topping gets a heluva hard time due the amount of shit they thrash through, along with stones,” Bruce Chowen of Central Contracting says.

“They are all right for the first couple of years and then the rot sets             in. A specialist topping mower is worth consideration in this case”.

Spreading. As an alternative to dropping the crop as it is mown, spreading will reduce the drying time. Adjustable swathing plates or swath formers on disc mowers allow a range of swath patterns. They may be used to simply flick the pasture in from the edge of the swath so there is a line to follow on the next pass and cut crop is not being run over.

Grass left in clumps tends to kill the grass underneath and promotes eczema spores. Maxam claim their mowers fitted with the Wilter Spreader are the only mowers that can cut, condition, and spread pasture in one pass without driving on the cut crop.

Windrowing: Maxam mowers with wilter tines removed windrow the cut pasture. With Krone mowers, the windrow width can be set to the tractor’s track width and tyre size to avoid tractor wheels running on the cut forage. On wet ground the mat is at risk of getting caked to the ground.

Wilters condition and spread the pasture out, allowing quicker drying.

Damage control. Side-mounted mowers have a breakaway system to minimise damage when an object like a fence post or trough is struck. The better systems automatically swing backwards and lift to clear the obstruction, and then swing and lower back into work position. All mowers have mechanisms to minimise damage to drive systems, with PTO clutches being popular. Others like the Kuhn GMD 240 FF have individual discs deactivating when something like wire is picked up. A heavy safety curtain should prevent damage to surrounds by containing debris. Kverneland claim their round discs are less susceptible to stone impacts than oval-shaped ones.

Hydraulic flotation. This keeps even pressure across the full width of the mower, less bounce at headland turns, and less movement of the mowing bar when travelling. This can be adjusted from the cab, or set to automatic on mowers like the Pottinger A10. The same effect is achieved on mowers like the Maxam 3300 which uses two heavy duty compression springs to transfer weight of the mower onto the tractor, allowing the mower to ride lightly across the ground.

Auto swathers (aka groupers). These are essentially a conveyor belt which fits to the back of the mower and shifts the row mown on to the previous row. They are suitable for long, mature baleage or silage crops, to limit drying and allow harvesting without windrowing.

Blade design. This affects picking up and mowing of grass flattened by the tractor wheel, with Maxam claiming their mowers blades are designed to do this. Blades should be easily reversed and changed.

Pivot angle, to cater for sloping ground. (up to 35 degrees is possible)

Maintenance. Many disc mowers have an enclosed oil bath in the disc mower’s cutter bar, for minimum maintenance. Individual disc removal for servicing or repairs is preferable.

Lighting, where road transport after dark is anticipated.

Hydraulic folding for transport is featured on most models, with folding up past 90 degrees giving better balance. Bigger units may swing aft in line with the tractor.

Transport height and length.

Support Trestle for storage.

Optional Equipment: Swathing discs, feed cones, wear skids.